This invention relates generally to engine driven, electrical generators, and in particular, to a control system for controlling operation of the engine and the electrical generator driven therewith.
Electrical generators are used in a wide variety of applications. As is conventional, electrical generators utilize a single driving engine coupled to a generator or alternator through a common shaft. Upon actuation of the engine, the crankshaft rotates the common shaft so as to drive the alternator which, in turn, generates electrical power.
Typically, an individual electrical generator operates in either a stand-by mode or a parallel mode. In the stand-by mode, the electrical power provided by a utility is monitored such that if the commercial electrical power from the utility fails, the engine of the electrical generator is automatically started causing the alternator to generate electrical power. When the electrical power generated by the alternator reaches a predetermined voltage and frequency desired by the customer, a transfer switch transfers the load imposed by the customer from the commercial power lines to the electrical generator.
Alternatively, in the parallel mode, the electrical generator supplies electrical power in parallel with the utility grid. As such, the electrical power generated by the electrical generator must be synchronized with the commercial electrical power supplied by the utility. Typically, multiple items such as governors, voltage regulators and the like are required to synchronize the electrical power generated by the electrical generator with the commercial electrical power supplied by the utility. This additional equipment is provided in separate cabinet units from the electrical generator itself, which adds significantly to the cost of the electrical generator.
Therefore, it is a primary object and feature of the present invention to provide an electrical generator incorporating a control system which controls operation of the electrical generator in a stand-by mode or a parallel mode.
It is a further object and feature of the present invention to provide an electrical generator which has the ability to supply electrical power to a load independent of the utility grid, or which may supply electrical power in parallel with the utility grid.
It is a still further object and feature of the present invention to provide an electrical generator which is simple to operate and less expensive to manufacture than prior electrical generators.
In accordance with the present invention, a control system is provided for controlling operation of an engine driven, electrical generator. The electrical generator generates AC power and AC voltage for a load. The AC power has a magnitude and a power factor and the AC voltage has a magnitude and a frequency. The control system includes a generator control operatively connected to the engine for controlling operation thereof and operatively connected to the generator for controlling the AC power generated thereby. A communications link operatively connects the generator control to a network.
A user interface is operatively connected to the network. The user interface allows the user to communicate with the generator control so as set predetermined operating parameters of the engine and the generator.
The control system may include a transfer switch having a first input connectable to a utility source for providing AC power, a second input operatively connected to the generator, and an output connectable to the load. The transfer switch is selectively movable between a first position connecting the utility source to the load and a second position connecting the generator to a load. The transfer switch is also operatively connected to the generator control such that the generator control controls movement of the transfer switch between the first and second positions.
It is contemplated to interconnect the load to a utility source which provides AC power having a magnitude and a power factor and AC voltage having a magnitude and a frequency. The control system includes a synchronizer for determining the magnitude and frequency of the AC voltage of the utility source and a magnitude and frequency of the AC voltage generated by the generator. The synchronizer is operatively connected to the generator control. The generator control varies the magnitude and frequency of the AC voltage generated by the generator to match the magnitude and frequency of the AC voltage provided by the utility source. A switch is operatively connected to the generator control and is movable between a first closed position for interconnecting the generator and the load and a second open position. The generator control moves the switch to the closed position in response to the magnitude and frequency of the AC voltage generated by the generator being generally equal to the magnitude and frequency of the AC voltage provided by the utility source.
The generator control may include a digital governor connectable to the engine for controlling the engine speed of the engine. The digital governor includes a throttle valve movable between a first opened position where the engine speed is at maximum and a second closed position where the engine speed is at minimum. The generator control may also include a volt-ampere-reactive (VAR) control for varying the power factor of the AC power generated by the generator to the predetermined level. In addition, the generator control includes a voltage regulator for controlling the magnitude of the AC voltage generated by the generator. An alarm system is connectable to the engine for monitoring various engine parameters. The alarm system communicates with the generator control and generates an alarm signal in response to a predetermined condition on the engine.
In accordance with a further aspect of the present invention, a generator structure is provided for generating AC power for a load. The generator structure includes a generator connectable to a load. The generator generates AC power having a magnitude and a power factor and an AC voltage having a magnitude and a frequency. An engine is operatively connected to the generator for driving the generator. The engine has an adjustable engine speed. A generator control is operatively connected to the engine for controlling operation thereof and is operatively connected to the generator for controlling AC power generated thereby. A communications link operatively connects the generator control to a network.
The generator structure may include a transfer switch having a first input connectable to a utility source for providing AC power, a second input operatively connected to the generator and an output connectable to the load. The transfer switch is selectively movable between a first position for connecting the utility source to the load and a second position for connecting the generator to the load. The transfer switch is operatively connected to the generator control such that the generator control controls movement of the transfer switch between first and second positions in response to AC power supplied by the utility source.
It is contemplated that the load be a utility source which provides AC power having a magnitude and a power factor and an AC voltage having magnitude and a frequency. The generator control includes a synchronizer for monitoring the magnitude and frequency of the AC voltage provided by the utility source and a magnitude and frequency of the AC voltage generated by the generator. The generator control varies the magnitude and frequency of the AC voltage generated by the generator to match the magnitude and frequency of the AC voltage of the utility source. The generator control may also include a volt-ampere-reactive (VAR) control for varying the power factor of the AC power generated by the generator.
A switch may be operatively connected to the generator control and be movable between a first closed position wherein the generator is connected to the utility source and a second open position. The generator control moves the switch to the closed position in response to the magnitude and frequency of the AC voltage generated by the generator being generally equal to the magnitude and frequency of the AC voltage provided by the utility source. The generator control includes a digital governor connected to the engine for controlling the engine speed of the engine. The digital governor includes a throttle valve which is movable between a first open position wherein the engine speed is at a maximum and a second closed position wherein the engine speed is at a minimum. A generator control includes a voltage regulator for regulating the magnitude of the AC voltage generated by the generator.
In accordance with a still further aspect of the present invention, a method is provided for providing AC power to a load. The method includes the steps of setting various operating parameters for a generator structure and transmitting the same to the generator structure over a network. AC power and AC voltage are generated with the generator structure in response to the various operating parameters set. The AC power has a magnitude and a power factor and the AC voltage has a magnitude and a frequency.
It is contemplated that the load be a utility source which provides AC power having a magnitude and a power factor and AC voltage having a magnitude and a frequency. The method includes the additional step of monitoring the magnitude and frequency of the AC voltage provided by the utility source and the magnitude and frequency of the AC voltage generated by the generator structure. The magnitude and frequency of the AC voltage generated by the generator structure is varied so as to match the magnitude and frequency of the AC voltage provided by the utility source. The generator structure and the utility source are interconnected in response to the magnitude and frequency of the AC voltage generated by the generator structure be generally equal to the magnitude and frequency of the AC voltage provided by the utility source.
In addition, the power factor of the AC power generated by the generator structure may be varied to a predetermined level and the AC voltage generated by the generator structure may be adjusted to a user selected magnitude.